One of the classes Kropf teaches in the university's petroleum technology program is about oil and gas drilling techniques, including hydraulic fracturing. While teaching that class one semester, he began to think about one of the largest problems with burning natural gas in order to create electricity -- the large amounts of carbon dioxide released into the atmosphere.

Carbon dioxide is a greenhouse gas that contributes to global warming.

In Kropf's process, the carbon dioxide created when natural gas is burned for energy would pass through special filters that would not only remove the gas, but also trap it.

When the filters had absorbed as much carbon dioxide as possible, they will be ready to serve a new purpose in oil and gas drilling.

The United States is in the middle of an energy boom due to a new drilling process called fracking, or hydraulic fracturing. In fracking, liquid and a sand-like material called a proppant are pumped down a well and create and hold open fissures in rock that allow oil or gas to be released. When the oil or gas begins to flow, most of the liquid is forced back up along with the oil or gas, but the proppant is left behind.

Kropf worked to develop a proppant that could also be used as a carbon dioxide-absorbing filter when fossil fuels are burned. With the carbon dioxide trapped inside, the proppant can then be pumped underground during the fracking process, sequestering the carbon dioxide underground.

It took Kropf four or five years to develop the perfect proppant. He began by speaking with local and national drilling companies to see if his idea was feasible.

Then he began studying materials that had not been considered before for use as proppants. It had to be something like sand, but that would chemically attract and bond to carbon dioxide. It had to have grains small enough to wedge themselves into rock and strong enough to keep it propped open. It could not dissolve in acid or water.

Kropf would have small batches developed and tested in labs. The money for the development came through a grant from the National Science Foundation's Innovation Corps Site at the University of Pittsburgh Innovation Institute. The Pitt Innovation Institute also helped him secure the patent for the eventual winner.

With the proppant developed, it could be licensed to companies for use, but currently, there is no financial incentive for U.S. energy companies to substantially reduce the amount of carbon dioxide they are producing. Should the federal government begin regulating or limiting carbon dioxide emissions - something many people think is a matter of when, not if -- Kropf's product is ready to go.